Chapter 5

In a body-centred cubic arrangement, A ions occupy the centre whil e B ions occupy corners of the cubic. The formula of the solid is. a) \(\mathrm{AB}_{2}\) b) \(\mathrm{AB}\) c) \(\mathrm{A}_{2} \mathrm{~B}\) d) None of these

Radius ratio \(r_{\mathrm{Na}}+/ r_{\mathrm{C} 1}^{-}\) in \(\mathrm{NaCl}\) crystal is a) \(0.524\) b) \(0.414\) c) \(0.732\) d) \(0.80\)

The number of atoms per unit cell in simple cubic, face-centred cubic and body-centred cubic are: a) \(1,4,2\) b) \(4,1,2\) (c) \(2,4,1\) (d) 4, 8, 2

Crystals can be classified into (a) 7 systems b) 9 systems c) 10 systems

Close packing is maximum in the crystal lattice of (a) face-centred cubic (b) \(\mathrm{BCC}\) (c) simple cubic

Bragg's equation is a) \(2 \cap \Lambda=d \sin \theta\) b) \(n \lambda=2 d \sin \theta\) c) \(\frac{n}{\lambda}=d \sin \theta\)

In Bragg's equation for diffraction of X-rays, \(n\) represents a) number of moles b) quantum number c) order of reflection d) Avogadro number

Total number of planes, axes and centre of symmetries in a crystal is termed as a) elements of symmetry (b) symmetries c) symmetry operations

If in a crystal intercepts are \(1, \infty\) and \(\infty\), the Millar indices are: (a) (100) (b) \((101)\) (c) (110) (d) (000)

Millar indices in a crystal indicate (a) designation of plane crystals (b) intercepts of plane on \(\mathrm{X}\) -axis (c) reciprocals of fractional intercepts of that plane on various axes (c) none